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6-6 Troubleshooting Guide
Troubleshooting
Data is garbled or lost
Check the modem’s flow control
settings.
• Ensure that the DTE's flow control is the same as the
modem setting
(for example, XON-XOFF, RTS/CTS).
• If your communications package’s file transfer
protocol is used,
and
the package supports RTS/CTS
Flow control, set Flow=RTS/CTS (AT
*
FL3). If the
package does not support RTS/CTS flow control, set
Flow=Off (AT
*
FL0).
Check that the modem’s DTE
rate, parity, and character length
match the DTE’s settings.
If they do not match, adjust as necessary.
If in normal mode, check line
quality:
• Check CQMS parameters
(signal quality and error
probability).
• Run a remote digital
loopback (RDL) or RDL
with pattern test.
If no errors occur, the line is good.
If errors occur, perform a manual retrain, or retry the
phone call.
• If you are still receiving
errors, disconnect the
modem from the line and
perform a local analog
loopback (LAL) or LAL
with pattern test (with
modem flow control off).
If the LAL or LAL with pattern test fails, contact Telenet-
ics Customer Support or your local distributor.
If the LAL or LAL with pattern test passes, you may have
a line problem (contact your telephone company) or a
problem with your application (check with your software
vendor).
Data stops passing
Modem could be in “flow off”
condition (modem set for XON-
XOFF and DTE set for hardware
flow control).
• Set the modem for hardware flow control.
• Set Flow=Off (AT
*
FL0).
The modem connects at
a lower rate than the
maximum (as set in the
Max Rate (AT
*
MX)
option)
Check CQMS parameters for
line quality.
Line quality is not sufficient to support higher data rate. If
line quality improves, the modem will increase its speed
automatically.
Ensure that the remote modem
supports the DCE rates you
anticipate.
Excessive modem
retrains
Retry call. Continuous retrains indicate a line problem. Contact your
telephone company.
326X Series Modem Troubleshooting Guide (Continued)
Problem Diagnosis/Test Possible Solution